Navman FISH 4500/4600 - Manual (Page 5)

1-2 How the FISH 4500/4600 works
The FISH 4500/4600 has two parts:
- the transducer attached to the hull
- the display unit.
The transducer generates an ultrasonic pulse
(sound that is above the hearing range of the
human ear), which travels down towards the
bottom at a speed of about 4800 ft/sec (1463 m/
sec), spreading out into a cone shape.
When the pulse meets an object, such as a
fish or the bottom, it is partly reflected back
up towards the boat as an echo. The depth
of the object or bottom is calculated by the
FISH 4500/4600 by measuring the time taken
between sending a pulse and receiving the
echo. When an echo has been returned, the
next pulse is sent.
The FISH 4500/4600 converts each echo into
an electronic signal, displayed as a vertical line
of pixels. The most recent echo appears on the
extreme right of the display, with the older echoes
being scrolled towards the left, eventually disap-
pearing off the display.
The scroll speed depends upon the water depth
and scroll speed setting. See section 3-2 Setup
> Sonar and section 4-1 Interpreting the display,
for more information.
The appearance of echoes displayed are af-
fected by:
• the fishfinder settings (frequency selected,
range and gain settings)
• echoes (different fish types, different bot-
tom types, wrecks and seaweed)
• noise (water clarity and bubbles).
See section 4-1 Interpreting the display, for more
information.
FISH 4500/4600 Installation and Operation Manual 5 NAVMAN